Battery Management System Communication Fault Detection
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Solution Overview
Problem
Existing battery management systems lack effective redundancy in detecting communication faults at voltage monitoring ICs, which can lead to unsafe conditions due to undetected errors in serial communication bus messages.
Innovation Solution
The battery management system employs first and second diagnostic flags, using CRC, communication time-out, and timing error bits to redundantly detect faults, with encoded fault values having a Hamming distance of at least four, ensuring safe action is taken when faults are indicated, such as transitioning a contactor to an open operational position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single diagnostic flag is used to detect communication faults, then the system complexity is reduced, but the reliability of fault detection is insufficient
Solution Approach 1:
The patent implements separate diagnostic flags (first CRC diagnostic flag, second CRC diagnostic flag, first communication time-out diagnostic flag, second communication time-out diagnostic flag) for different fault types and detection instances. Each flag independently monitors specific communication faults, allowing localized detection without requiring a single complex centralized diagnostic system. This resolves the contradiction by improving reliability through multiple specialized flags while keeping each flag's logic relatively simple.
Solution Approach 2:
The diagnostic system is segmented into multiple independent diagnostic flags, each responsible for detecting specific fault conditions (CRC errors, communication time-outs). The microcontroller divides the diagnostic function across multiple applications (first application, second application), where each application sets specific flags based on their respective diagnostic bits. This segmentation improves reliability by distributing detection responsibilities while maintaining manageable complexity through modular design.
2Reliability
If redundant diagnostic flags are implemented, then the reliability of fault detection is improved, but the device complexity increases
Solution Approach 1:
The patent uses multiple diagnostic flags that are essentially copies of the same diagnostic functionality, each monitoring specific communication faults. The first and second applications both perform CRC checks and time-out detections, setting corresponding flags independently. This copying approach improves reliability through redundant detection while keeping the implementation simple by reusing the same diagnostic logic across multiple instances.
Solution Approach 2:
The patent employs encoded fault values with Hamming distance of at least four for the diagnostic flags. This parameter change in the error encoding scheme allows the system to detect and correct a greater number of bit errors in the flag signals themselves, improving the reliability of the redundant flags while the encoding overhead remains manageable.
3Measurement precision
If encoded fault values with Hamming distance of at least four are used, then the error detection capability is improved, but the processing complexity increases
Solution Approach 1:
The patent pre-defines encoded fault values with Hamming distance of at least four in the microcontroller's memory or lookup tables. Instead of performing complex real-time encoding calculations, the system stores pre-computed encoded values and simply compares diagnostic results against these predefined patterns. This preliminary preparation improves error detection precision while significantly reducing the processing complexity during actual fault detection operations.
Data Source
AI summary
A battery management system includes a microcontroller having first and second applications. The first application transitions a contactor to an open operational position if a first CRC diagnostic flag is equal to a first encoded fault value. The second application transitions the contactor to the open operational position if a second CRC diagnostic flag is equal to a second encoded fault value. The first and second encoded fault values have a Hamming distance of at least four from one another.